National Teams

In my current game i manage a club team...Is possible to manage also a national team?If yes...what i need to do?

Yes it is, if you haven't started yet, when picking a team there is an option at the top to manage national and club team, if you have started, wait until an international manager is sacked and then apply for the job as you would any club job and you can manage both at once

How long does it take to get an answer after i applied to the job?

Couple of days usually. If you have a higher reputation you are more likely to get the job.